Process for flame refining of copper smelts

ABSTRACT

IN A FLAME REFINING PROCESS OF COPPER SMELTS IN A ROTARY CALCINER WHEREIN OXYGEN IS BLOWN THROUGH AN INDIVIDUAL NOZZLE OR LANCE TO THE FLAME BURNING IN THE FURNACE, THE OXYGEN IS BLOWN SO THAT ITS EFFECT ON THE SMELTING CHARGE IS TO OXIDIZE A CONSIDERABLE PORTION OF THE CHARGE DURING SMELTING, WITH THE HIGHEST FLAME TEMPERATURE BEING ON THE UNDERSIDE OF THE FLAME.

May 11, 1971 (EN ETAL 3,578,438

PROCESS FOR FLAME REFINING OF COPPER S MELTS Filed Oct. 10. 1967 United States Patent 3,578,438 PROCESS FOR FLAME REFINING OF COPPER SMELTS Horst Dieter Iken, Dusseldorf, and Wolfgang Hans Trappmann, Heiligenhaus, Germany, assignors to Messer Griesheim GmbH, Frankfurt am Main, Germany Filed Oct. 10, 1967, Ser. No. 674,188 Claims priority, applicatigri 1 Gzgrmany, Oct. 19, 1966,

US. Cl. 75-73 2 Claims ABSTRACT OF THE DISCLOSURE In a flame refining process of copper smelts in a rotary calciner wherein oxygen is blown through an individual nozzle or lance to the flame burning in the furnace, the oxygen is blown so that its elfect on the smelting charge is to oxidize a considerable portion of the charge during smelting, with the highest flame temperature being on the underside of the flame.

BACKGROUND OF THE INVENTION Impurities of copper smelts, such as lead, bismuth, tin, antimony, nickel, cobalt, zinc, iron, gold, silver, sulfur, selenium, tellurium, and others, are removed by refining. This can occur by means of refining in the smelting flow (i.e. flame refining) or by electrolytic refining. One selects either flame or electrolytic refining according to the type and amount of the impurities, the content of precious metals and the desired degree of purification of the finished copper.

In refining in the smelting flow or flame refining the impurities are mainly removed by oxidation and sintering of oxides. Oxidation begins even during the smelting. The melting time, for example, in a to-rotary calciner amounts to four hours. The oxidation is intensified in the blowing time, by blowing in of oxygen or air containing oxygen. There results in the copper, dissolved copper-I-oxide (Cu O), which acts as the oxygen transmitter on the impurities. The blowing time of a 30 to-rotary calciner with air amounts to about three hours, while with oxygen only about one-half hour.

Upon termination of the oxidation, the dissolved Cu O is again reduced by dipping of fresh oak or birch stems. This so-called poling of copper consists of two partial steps. In the first action, the seal poling, the Water vapor freed from the wood and the polar gases (mainly H wash away the S0 present in the copper and constantly developing as a result of the reaction between Cu S and C1120.

In the second action, the toughening by poling, Cu O is reduced. The melt is covered with charcoal or coke poor in sulphur in order to speed up the reaction. The oxygen content of the toughened copper is between 0.0-2-0.5%.

The welding in the refining kiln takes place by a gas-, coal dustor oil-flaming (fuel-air-gas mixture).

It is known that the welding time can be shortened by oxygen enrichment of the furnace air or lower-shaft addition of oxygen under the flame. Furthermore, instead of moving along with the oxide flame, the process of the 3,578,438 Patented May 11, 1971 refining can be carried out by blowing in and blowing up of compressed air, of air enriched with oxygen or of oxygen. With this known process the refining time is also considerably reduced.

SUMMARY OF INVENTION The gist of the invention is still further to shorten the process for the flame refining of copper smelts and thus make it more economical.

This object is advantageously achieved by the invention in that the blowing of oxygen into the furnace takes place in that, by the effect of pure oxygen on the melting charge, a considerable part of the charge is already oxidized during the smelting and that the highest temperatures of the flame are at its underside. The blowing time in the novel process is already partially advanced into the smelting time, i.e. a portion of the oxidation necessary for the elimination of the impurities is already undertaken during the smelting.

The novel process has the advantage of the greater heat transfer to the charge, which has the consequence of a decrease of the fuel expenditure and/or an increase in the capacity of the furnace. The smelting time is shortened by the elimination of the nitrogen ballast and the thereby resulting high temperatures. A further decrease in the smelting time is possible by the heat released in the oxidation to Cu O. A further advantage is the decrease in the blowing time, which leads to a considerable capacity increase.

In a further advantageous development of the invention, it is recommended to direct the oxygen stream di rectly to the smelting charge, whereby it is then deflected from its surface to the flame underside.

THE DRAWINGS The carrying out of the novel process is better understood by reference to the single figure which illustrates the process in conjunction with a rotary calciner.

DETAILED DESCRIPTION The rotary calciner 1 has a supply conduit 2 with nozzle 3 for the fuel, e.g., gas, coal dust and oil, or mixtures thereof. The oxygen is supplied through the water-cooled oxygen lance or nozzle 4 which is movable on a carriage 5 and has at its end an adjustable mouthpiece or outlet 6 directed away from the axis of lance 4. Conduits 7 and 8 supply and discharge coolant water for lance 4. The initially solid smelting charge, consisting essentially of copper sulfide and other conventional copper ore unrefined metal compounds, is designated with 10 and the flue of the rotary calciner with 11. From nozzle 3 the fuel feeding flame 12 emerges and the oxygen stream 13 emerges from mouthpiece 6 where it first contacts the smelting charge and is then deflected by it to the flame underside. In such a manner, already during the smelting, a considerable portion of the smelting charge is oxidized by the effect of pure oxygen.

The novel process is in no way limited to the rotary calciner illustrated in the drawing. The inventive process can be employed with success with respect to otherwise constructed furnaces.

What is claimed is:

1. In an improved process for the furnace refining of a copper smelt to the metal oxide for subsequent metal recovery, comprising feeding a copper containing charge into a rotary furnace, smelting said charge by directing H a substantially horizontal fuel fed flame into the furnace, and simultaneously introducing pure oxygen into the furnace in an amount suflicient both to oxidize the charge by coming into direct contact with the charge and to accelerate the smelting by materially increasing the flame temperature.

2. In the process of claim 1 wherein the oxygen is directed toward the smelt and a portion of the oxygen is substantially deflected off said smelt to the flame underside.

- UNITED STATES PATENTS- Graef 75-6OX Kurzinski 7543X Kurzinski 7543 Spitz 7573 US. Cl. X.R. 

